Tobacco products and process therefor



nitcd States Patet- 2,897,103 Patented July 28, 1959 Alfred M. Gottscho,Lancaster, Pa., assignor to General Cigar Co., Inc., New York, N.Y., acorporation of New ork N Drawing. Application August 5, 1957 Serial No.676,391

12 Claims. (Cl. 131-17) This invention relates to tobacco productssuitable for smoking, and more particularly to tobacco products formedof comminuted tobacco and a binding agent forthe tobacco particles.

U.S. Patents 2,592,553 of W. G. Frankenburg and P. W. Garbo and2,592,554 of W. G. Frankenburg, both issued April 15, 1952, describedthe production of tobacco sheets by mixing tobacco particles with anaqueous solution of a water-soluble binding agent, like methyl celluloseor sodium alginate, to form a paste which is spread as a thin layer andthen dried. As disclosed in US. Patent 2,797,689 of W. G. Frankenburg,issued July 2, 1957, such tobacco products may also be made ofcomminuted tobacco and water-insoluble binding agents. The commercialsuccess of converting tobacco into continuous sheets is attributable toimproved smoking qualities resulting from the disintegration of tobaccoveins and stems and from the intimate blending of several tobaccos.However, in the utilization of these tobacco sheets, for instance, asbinders in cigars, some dilficulty has been encountered because oftearing and rupturing. Research has recently been directed to improvingthe strength of tobacco sheets without adding any new component.

It has now been discovered that a narrow range of fine particle sizesmaterially increases the tensile strength of tobacco sheets producedfrom such finely divided to bacco and a binding agent. The criticalnessof particle size of the comminuted tobacco long escaped attentionbecause it was not anticipated that very small amounts of somewhatcoarser particles could appreciably lower the tensile strength of thetobacco sheet produced therefrom. Thus, US. Patent 2,706,695 of W. G.Frankenburg issued April 19, 1955, disclosed in Example 3 a tobaccosheet made of ground tobacco having a screen analysis of 2.8% by weightretained on a SO-mesh screen and 82% passing through ZOO-mesh. In spiteof the comparatively fine powder used in the aforesaid patent, thetensile strength obtained with a tobacco sheet made of ground tobaccocontaining as much as 2.8% by weight of particles coarser than 80-meshfalls far short of the tensile strengths now attainable pursuant to thisinvention. Unexpectedly high tensile strengths are obtained when tobaccois dry ground to a powder having a screen analysis of more than 99% byweight through a 100-mesh screen and more than 86% through ZOO-mesh.Preferably, more than 95% by weight of the tobacco powder should passthrough a ZOO-mesh screen. Studies have shown that the predominant part,usually at least 70 by weight, of the particles which pass through theZOO-mesh screen should have maximum dimensions in the range of 40 to 65microns for optimum results.

The surprisingly disproportionate decrease of tensile strength oftobacco sheets resulting from the presence of a very small amount oftobacco particles coarser than 100-mesh is illustrated by a series oftests made with a German cigar tobacco. This tobacco was dry ground toobtain three batches of tobacco powder of the following screen analyses:

Batch A B C Percent Percent Percent 011 100-mesh... 1. 6 0. 0 0.0 011200-mesh 18.4 11. 7 1.8 On 325mesh 79. 7 86.0 94. 1 Thru 325-mesh O. 32. 3 4. 1

Batch A was ground in a Gruendler pulverizer (hammertype mill withhorizontal shaft), batch B was first passed through the Gruendlerpulverizer and then through a Mikro-Bud grinder. (hammer-type mill withvertical shaft), and batch C was twice ground in a Shutz-ONeillpulverizer (mill with beater plates having fixed hammers).' t

Each batch of ground German tobacco was converted to a tobacco sheetusing the same procedure and formulation in each instance. For each 100weight parts of tobacco powder, there were used 14.7 parts of methyl cellulose (400 centipoise grade), 22.8 parts of triethylene glycol, 6.3parts of diatomaceous-earth, 6.3 parts of finely powdered siliceouscatalyst, and sufiicientwater to form a 2.5% by weight solution of themethyl cellulose.

Samples of the tobacco sheets produced from the three batches of groundGerman tobacco were subjected Iunder the same conditions to. tensilestrength tests. The sheet made of batch. A tobacco powder had a tensilestrength of grams per square millimeter, that of batch B 145 grams persquare millimeter and that of, batch C 190 grams per square millimeter.Accordingly, by eliminating only 1.6% by weight of tobacco particlescoarser than -mesh and decreasing the amount of tobacco powdercoarserthan ZOO-mesh from 18.4% to 11.7% by weight, the tensile strengthof the tobacco sheet was increased about 60%. In the case of batch Ctobacco powder, the sheet showed an improvement in tensile strength ofover 100% when compared with the sheet made of batch A tobacco powder.

In another series of tests, three batches of a blend of American cigartobaccos were dry ground in the Mikro- Bud pulverizer to differentdegrees of particles fineness as shown by the following screen analyses:

In batch F, approximately 80% by weight of the tobacco particles finerthan ZOO-mesh had maximum dimensions in the range of 40 to 65 microns.

Following the same procedure and formulation, each batch of ground cigartobacco was converted to a tobacco sheet. Each 100 weight parts oftobacco powder were combined with 14.7 parts of methyl cellulose (4000centipoise grade), 22.8 parts of triethylene glycol, 6.3 parts ofdiatomaceous earth, 6.3 parts of finely powdered siliceous catalyst, andsufficient water to form a 2% by weight solution of the methylcellulose. The resulting pasty mixture was spread in a thin layer anddried to a coherent tobacco sheet.

Tensile strength tests under the same conditions were performed onsamples of the tobacco sheets produced from the three "batches of groundcigar tobacco. The sheet made of batch D tobacco powder had a tensilestrength of 90 grams per square millimeter, that of batch E grams persquare millimeter and that of batch F grams per square millimeter. Inspite of the batch F powders were increased nearly 40% and 85%.

This series of tests illustrates that, if tobacco sheets of high tensilestrength are to be produced, it is not sulficient to grind the tobaccoso that substantially all of the particles pass through a IOO-meshscreen, but that it is also necessary to grind the tobacco so that morethan 86% by weight of the particles will pass through a 200- meshscreen. When at least 70% by weight of the particles finer than 200-meshhave maximum dimensions in the range of 40 to 65 microns, an optimumtensile strength is obtained.

What is claimed is:

1. In tobacco smoking products in which particles of dry ground tobaccoare held together in a coherent form 'by a binding agent, theimprovement of tobacco dry ground to particles of which more than 99% byWeight pass through a lOO-rnesh screen and more than 86% by weightpassthrough a ZOO-mesh screen to yield increased tensile strength in saidcoherent form.

2. The tobacco smoking products of claim 1 wherein the binding agent ismethyl cellulose.

3. The tobacco smoking products of claim 1 wherein at least 70% byweight of the particles passing through a ZOO-mesh screen have maximumdimensions in the range of 40 to 65 microns.

4. The tobacco smoking products of claim 3 wherein the binding agent isa Water-soluble cellulose derivative.

5. In the process of converting tobacco into a continuous and coherentform by comminuting tobacco and adhering the resulting particles oftobacco to one another with a binding agent, the improvement of grindingdry tobacco to particles more than 99% by weight of which pass through aIOO-mesh screen and more than 86% by weight of which pass through aZOO-mesh screen in order to increase the tensile strength of thecontinuous and coherent form resulting from the adhesion of saidparticles to one another with a binding agent.

6. The process of claim 5 wherein the binding agent is methyl cellulose.

7. The process of claim 5 wherein the grinding of dry tobacco toparticles more than 86% by weight of which pass through a ZOO-meshscreen yields particles with maximum dimensions in the range of tomicrons in an amount at least by weight of the particles passing througha ZOO-mesh screen.

8. The process of claim 5 wherein the grinding of dry tobacco iseffected in a hammer-type mill.

9. The process of converting tobacco into a continuous sheet of improvedtensile strength, which comprises dry grinding tobacco to particles morethan 99% by weight of which pass through a lOO-mesh screen and more thanby weight of which pass through a 200- mesh screen, admixing saidparticles With an aqueous solution of a binding agent, spreading theresulting admixture of said particles and said solution as a continuousfilm and drying said film to yield a continuous sheet of improvedtensile strength.

10. The process of claim 9 wherein at least 70% by weight of theparticles which pass through a ZOO-mesh screen have maximum dimensionsin the range of 40 to 65 microns;

11. The process of of tobacco is effected in a 12. The process of claimis methyl cellulose.

claim 10 wherein the dry grinding hammer-type mill.

10 wherein the binding agent References Cited in the file of this patent

1. IN TOBACCO SMOKING PRODUCTS IN WHICH PARTICLES OF DRY GROUND TOBACCOARE HELD TOGETHER IN A COHERENT FORM BY A BINDING AGENT, THE IMPROVEMENTOF TOBACCO DRY GROUND TO PARTICLES OF WHICH MORE THAN 99% BY WEIGHT PASSTHROUGH A 100-MESH SCREEN AND MORE THAN 86% BY WEIGHT PASS THROUGH A200-MESH SCREEN TO YIELD INCREASED TENSILE STRENGTH IN SAID COHERENTFORM.